Photoresist composition and method of forming photoresist pattern

ABSTRACT

A method of forming a photoresist pattern includes forming a protective layer over a photoresist layer formed on a substrate, and selectively exposing the photoresist layer to actinic radiation. The photoresist layer is developed to form a pattern in the photoresist layer, and the protective layer is removed. The protective layer includes a polymer having fluorocarbon pendant groups.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Patent Application62/585,765 filed Nov. 14, 2017, the entire disclosure of which isincorporated herein by reference.

TECHNICAL FIELD

The disclosure relates to photoresist compositions and methods offorming photoresist patterns in a semiconductor manufacturing processes.

BACKGROUND

As consumer devices have gotten smaller and smaller in response toconsumer demand, the individual components of these devices havenecessarily decreased in size as well. Semiconductor devices, which makeup a major component of devices such as mobile phones, computer tablets,and the like, have been pressured to become smaller and smaller, with acorresponding pressure on the individual devices (e.g., transistors,resistors, capacitors, etc.) within the semiconductor devices to also bereduced in size.

One enabling technology that is used in the manufacturing processes ofsemiconductor devices is the use of photosensitive materials. Suchmaterials are applied to a surface and then exposed to an energy thathas itself been patterned. Such an exposure modifies the chemical andphysical properties of the exposed regions of the photosensitivematerial. This modification, along with the lack of modification inregions of the photosensitive that were not exposed, can be exploited toremove one region without removing the other.

However, as the size of individual devices has decreased, processwindows for photolithographic processing has become tighter and tighter.As such, advances in the field of photolithographic processing arenecessary to maintain the ability to scale down the devices, and furtherimprovements are needed in order to meet the desired design criteriasuch that the march towards smaller and smaller components may bemaintained.

Extreme ultraviolet lithography (EUVL) has been developed to formsmaller semiconductor device feature size and increase device density ona semiconductor wafer. As device features shrink the elimination ofdefects becomes more critical. Defects may be formed by the absorptionof contaminants, such as particles, moisture, and ammonia in aphotoresist during processing.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure is best understood from the following detaileddescription when read with the accompanying figures. It is emphasizedthat, in accordance with the standard practice in the industry, variousfeatures are not drawn to scale and are used for illustration purposesonly. In fact, the dimensions of the various features may be arbitrarilyincreased or reduced for clarity of discussion.

FIG. 1 illustrates a process flow according to embodiments of thedisclosure.

FIGS. 2A and 2B show process stages of sequential operations accordingto an embodiment of the disclosure.

FIGS. 3A, 3B, 3C, and 3D show process stages of sequential operationsaccording to an embodiment of the disclosure.

FIG. 4 shows a process stage of a sequential operation according to anembodiment of the disclosure.

FIG. 5 shows a process stage of a sequential operation according to anembodiment of the disclosure.

FIG. 6 shows a process stage of a sequential operation according to anembodiment of the disclosure.

FIG. 7 shows a process stage of a sequential operation according to anembodiment of the disclosure.

FIG. 8 shows photoresist polymer components according to embodiments ofthe disclosure.

FIG. 9 shows a process stage of a sequential operation according to anembodiment of the disclosure.

FIG. 10 shows a process stage of a sequential operation according to anembodiment of the disclosure.

FIG. 11 shows a process stage of a sequential operation according to anembodiment of the disclosure.

FIG. 12 shows a process stage of a sequential operation according to anembodiment of the disclosure.

FIG. 13 shows a process stage of a sequential operation according to anembodiment of the disclosure.

FIG. 14 shows a process stage of a sequential operation according to anembodiment of the disclosure.

DETAILED DESCRIPTION

It is to be understood that the following disclosure provides manydifferent embodiments, or examples, for implementing different featuresof the disclosure. Specific embodiments or examples of components andarrangements are described below to simplify the present disclosure.These are, of course, merely examples and are not intended to belimiting. For example, dimensions of elements are not limited to thedisclosed range or values, but may depend upon process conditions and/ordesired properties of the device. Moreover, the formation of a firstfeature over or on a second feature in the description that follows mayinclude embodiments in which the first and second features are formed indirect contact, and may also include embodiments in which additionalfeatures may be formed interposing the first and second features, suchthat the first and second features may not be in direct contact. Variousfeatures may be arbitrarily drawn in different scales for simplicity andclarity.

Further, spatially relative terms, such as “beneath,” “below,” “lower,”“above,” “upper” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. The spatiallyrelative terms are intended to encompass different orientations of thedevice in use or operation in addition to the orientation depicted inthe figures. The device may be otherwise oriented (rotated 90 degrees orat other orientations) and the spatially relative descriptors usedherein may likewise be interpreted accordingly. In addition, the term“made of” may mean either “comprising” or “consisting of.”

FIG. 1 illustrates a process flow 100 of manufacturing a semiconductordevice according to embodiments of the disclosure. A photoresist iscoated on a surface of a layer to be patterned or a substrate 10 inoperation S110, in some embodiments, to form a photoresist layer 15, asshown in FIGS. 2A and 2B. The photoresist includes a protective polymer20 that forms a protective layer over the photoresist layer 15, as shownin FIG. 2B. The photoresist/protective polymer mixture is dispensed froma dispenser 25. While the photoresist/protective polymer mixture isapplied or immediately thereafter, the substrate 10 is rotated. Whilethe substrate is rotated the protective polymer separates from thephotoresist composition and forms a protective layer 20 over thephotoresist layer 15. In some embodiments, the protective polymerseparates from the mixture because of its hydrophobicity relative to thephotoresist. The protective layer 20 prevents contaminants, includingparticles, moisture, and ammonia, from being absorbed into orimpregnating the photoresist layer 15.

Then the photoresist layer 15 and protective layer 20 undergo a firstbaking operation to evaporate solvents in the photoresist composition insome embodiments. The photoresist layer 15 and protective layer 20 arebaked at a temperature and time sufficient to cure and dry thephotoresist layer 15 and protective layer 20. In some embodiments, thelayers are heated to a temperature of about 40° C. and 250° C. for about10 seconds to about 10 minutes.

In other embodiments, the photoresist 15 is coated on a surface of alayer to be patterned or a substrate 10 in operation S110 to form aphotoresist layer 15, as shown in FIGS. 3A and 3B. As explained inreference to FIG. 2A, the photoresist is dispensed from a dispenser 25.While the photoresist is applied or immediately thereafter, thesubstrate 10 is rotated. Then the photoresist layer 15 undergoes a firstbaking operation to evaporate solvents in the photoresist composition insome embodiments. In some embodiments, the photoresist layer 15 isheated to a temperature of about 40° C. and 250° C. for about 10 secondsto about 10 minutes.

After the first baking operation, a protective layer 20 is coated on thephotoresist layer 15. As shown in FIGS. 3C and 3D. The protective layer20 is a protective polymer composition 20 dispensed from a dispenser 27,as shown in FIG. 3C. While the protective polymer composition is appliedor immediately thereafter, the substrate 10 is rotated.

Then the protective layer 20 undergoes a baking operation to evaporatesolvents in the protective polymer composition in some embodiments. Theprotective layer 20 is baked at a temperature and time sufficient tocure and dry the protective layer 20. In some embodiments, thephotoresist layer is heated to a temperature of about 40° C. and 250° C.for about 10 seconds to about 10 minutes.

After the photoresist and protective layers 15, 20 undergo the bakingoperation, the photoresist layer 15 and protective layer 20 areselectively exposed to actinic radiation 45 (see FIG. 4) in operationS130. In some embodiments, the ultraviolet radiation is deep ultravioletradiation. In some embodiments, the ultraviolet radiation is extremeultraviolet (EUV) radiation. In some embodiments, the radiation is anelectron beam. In some embodiments, the thickness of the protectivelayer 20 is sufficiently thin so that the protective layer 20 does notadversely affect the exposure of the photoresist layer 15 to theradiation 45. In some embodiments, the protective layer has a thicknessranging from about 0.1 nm to about 20 nm. In some embodiments, thethickness of the protective layer ranges from about 1 nm to about 15 nm.In some embodiments, the contact angle of the protective layer to wateris greater than 75°.

As shown in FIG. 4, the exposure radiation 45 passes through a photomask30 before irradiating the photoresist layer 15 in some embodiments. Insome embodiments, the photomask has a pattern to be replicated in thephotoresist layer 15. The pattern is formed by an opaque pattern 35 onphotomask substrate 40, in some embodiments. The opaque pattern 35 maybe formed by a material opaque to ultraviolet radiation, such aschromium, while the photomask substrate 40 is formed of a material thatis transparent to ultraviolet radiation, such as fused quartz.

The region of the photoresist layer exposed to radiation 50 undergoes achemical reaction thereby changing its solubility in a subsequentlyapplied developer relative to the region of the photoresist layer notexposed to radiation 52. In some embodiments, the portion of thephotoresist layer exposed to radiation 50 undergoes a crosslinkingreaction.

Next, the photoresist layer 15 and protective layer 20 undergo apost-exposure bake in operation S140. In some embodiments, thephotoresist layer 15 and protective layer 20 are heated to a temperatureof about 50° C. and 160° C. for about 20 seconds to about 120 seconds.The post-exposure baking may be used in order to assist in thegenerating, dispersing, and reacting of the acid/base/free radicalgenerated from the impingement of the radiation 45 upon the photoresistlayer 15 during the exposure. Such thermal assistance helps to create orenhance chemical reactions which generate chemical differences betweenthe exposed region 50 and the unexposed region 52 within the photoresistlayer. These chemical differences also cause differences in thesolubility between the exposed region 50 and the unexposed region 52.

The selectively exposed photoresist layer is subsequently developed byapplying a developer to the selectively exposed photoresist layer inoperation S150. As shown in FIG. 5, a developer 57 is supplied from adispenser 62 to the photoresist layer 15 and protective layer 20. Insome embodiments, the protective layer 20 and the unexposed region ofthe photoresist layer 52 are removed by the developer 57 forming apattern of openings 55 in the photoresist layer 15 to expose the layerto be patterned or substrate 10, as shown in FIG. 6.

In some embodiments, the pattern of openings 55 in the photoresist layer15 are extended into the layer to be patterned or substrate 10 to createa pattern of openings 55′ in the substrate 10, thereby transferring thepattern in the photoresist layer 15 into the substrate 10, as shown inFIG. 7. The pattern is extended into the substrate by etching, using oneor more suitable etchants. The exposed photoresist layer 50 is at leastpartially removed during the etching operation in some embodiments. Inother embodiments, the exposed photoresist layer 50 is removed afteretching the layer to be patterned or substrate 10 by using a suitablephotoresist stripper solvent or by a photoresist ashing operation.

In some embodiments, the substrate 10 includes a single crystallinesemiconductor layer on at least it surface portion. The substrate 10 mayinclude a single crystalline semiconductor material such as, but notlimited to Si, Ge, SiGe, GaAs, InSb, GaP, GaSb, InAlAs, InGaAs, GaSbP,GaAsSb and InP. In some embodiments, the substrate 10 is a silicon layerof an SOI (silicon-on insulator) substrate. In certain embodiments, thesubstrate 10 is made of crystalline Si.

The substrate 10 may include in its surface region, one or more bufferlayers (not shown). The buffer layers can serve to gradually change thelattice constant from that of the substrate to that of subsequentlyformed source/drain regions. The buffer layers may be formed fromepitaxially grown single crystalline semiconductor materials such as,but not limited to Si, Ge, GeSn, SiGe, GaAs, InSb, GaP, GaSb, InAlAs,InGaAs, GaSbP, GaAsSb, GaN, GaP, and InP. In an embodiment, the silicongermanium (SiGe) buffer layer is epitaxially grown on the siliconsubstrate 10. The germanium concentration of the SiGe buffer layers mayincrease from 30 atomic % for the bottom-most buffer layer to 70 atomic% for the top-most buffer layer.

In some embodiments, the substrate 10 includes at least one metal, metalalloy, and metal/nitride/sulfide/oxide/silicide having the formulaMX_(a), where M is a metal and X is N, S, Se, O, Si, and a is from about0.4 to about 2.5. In some embodiments, the substrate 10 includestitanium, aluminum, cobalt, ruthenium, titanium nitride, tungstennitride, tantalum nitride, and combinations thereof.

In some embodiments, the substrate 10 includes a dielectric having atleast silicon, metal oxide, and metal nitride of the formula MX_(b),where M is a metal or Si, X is N or O, and b ranges from about 0.4 toabout 2.5. Ti, Al, Hf, Zr, and La are suitable metals, M, in someembodiments. In some embodiments, the substrate 10 includes silicondioxide, silicon nitride, aluminum oxide, hafnium oxide, lanthanumoxide, and combinations thereof.

The photoresist layer 15 is a photosensitive layer that is patterned byexposure to actinic radiation. Typically, the chemical properties of thephotoresist regions struck by incident radiation change in a manner thatdepends on the type of photoresist used. Photoresist layers 15 aretypically positive resists or negative resists. Conventionally, positiveresist refers to a photoresist material that when exposed to radiation(typically UV light) becomes soluble in a developer, while the region ofthe photoresist that is non-exposed (or exposed less) is insoluble inthe developer. Negative resist, on the other hand, conventionally refersto a photoresist material that when exposed to radiation becomesinsoluble in the developer, while the region of the photoresist that isnon-exposed (or exposed less) is soluble in the developer. The region ofa negative resist that becomes insoluble upon exposure to radiation maybecome insoluble due to a cross-linking reaction caused by the exposureto radiation.

Whether a resist is a positive or negative may depend on the type ofdeveloper used to develop the resist. For example, some positivephotoresists provide a positive pattern, (i.e.—the exposed regions areremoved by the developer), when the developer is an aqueous-baseddeveloper, such as a tetramethylammonium hydroxide (TMAH) solution. Onthe other hand, the same photoresist provides a negative pattern(i.e.—the unexposed regions are removed by the developer) when thedeveloper is an organic solvent. Further, in some negative photoresistsdeveloped with the TMAH solution, the unexposed regions of thephotoresist are removed by the TMAH, and the exposed regions of thephotoresist, that undergo cross-linking upon exposure to actinicradiation, remain on the substrate after development.

Photoresists according to the present disclosure include a polymer resinalong with one or more photoactive compounds (PACs) in a solvent, insome embodiments. In some embodiments, the polymer resin includes ahydrocarbon structure (such as an alicyclic hydrocarbon structure) thatcontains one or more groups that will decompose (e.g., acid labilegroups) or otherwise react when mixed with acids, bases, or freeradicals generated by the PACs (as further described below). In someembodiments, the hydrocarbon structure includes a repeating unit thatforms a skeletal backbone of the polymer resin. This repeating unit mayinclude acrylic esters, methacrylic esters, crotonic esters, vinylesters, maleic diesters, fumaric diesters, itaconic diesters,(meth)acrylonitrile, (meth)acrylamides, styrenes, vinyl ethers,combinations of these, or the like.

Specific structures that are utilized for the repeating unit of thehydrocarbon structure in some embodiments, include one or more of methylacrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butylacrylate, isobutyl acrylate, tert-butyl acrylate, n-hexyl acrylate,2-ethylhexyl acrylate, acetoxyethyl acrylate, phenyl acrylate,2-hydroxyethyl acrylate, 2-methoxyethyl acrylate, 2-ethoxyethylacrylate, 2-(2-methoxyethoxy)ethyl acrylate, cyclohexyl acrylate, benzylacrylate, 2-alkyl-2-adamantyl (meth)acrylate ordialkyl(1-adamantyl)methyl (meth)acrylate, methyl methacrylate, ethylmethacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butylmethacrylate, isobutyl methacrylate, tert-butyl methacrylate, n-hexylmethacrylate, 2-ethylhexyl methacrylate, acetoxyethyl methacrylate,phenyl methacrylate, 2-hydroxyethyl methacrylate, 2-methoxyethylmethacrylate, 2-ethoxyethyl methacrylate, 2-(2-methoxyethoxy)ethylmethacrylate, cyclohexyl methacrylate, benzyl methacrylate,3-chloro-2-hydroxypropyl methacrylate, 3-acetoxy-2-hydroxypropylmethacrylate, 3-chloroacetoxy-2-hydroxypropyl methacrylate, butylcrotonate, hexyl crotonate, or the like. Examples of the vinyl estersinclude vinyl acetate, vinyl propionate, vinyl butylate, vinylmethoxyacetate, vinyl benzoate, dimethyl maleate, diethyl maleate,dibutyl maleate, dimethyl fumarate, diethyl fumarate, dibutyl fumarate,dimethyl itaconate, diethyl itaconate, dibutyl itaconate, acrylamide,methyl acrylamide, ethyl acrylamide, propyl acrylamide, n-butylacrylamide, tert-butyl acrylamide, cyclohexyl acrylamide, 2-methoxyethylacrylamide, dimethyl acrylamide, diethyl acrylamide, phenyl acrylamide,benzyl acrylamide, methacrylamide, methyl methacrylamide, ethylmethacrylamide, propyl methacrylamide, n-butyl methacrylamide,tert-butyl methacrylamide, cyclohexyl methacrylamide, 2-methoxyethylmethacrylamide, dimethyl methacrylamide, diethyl methacrylamide, phenylmethacrylamide, benzyl methacrylamide, methyl vinyl ether, butyl vinylether, hexyl vinyl ether, methoxyethyl vinyl ether, dimethylaminoethylvinyl ether, or the like. Examples of styrenes include styrene, methylstyrene, dimethyl styrene, trimethyl styrene, ethyl styrene, isopropylstyrene, butyl styrene, methoxy styrene, butoxy styrene, acetoxystyrene, chloro styrene, dichloro styrene, bromo styrene, vinyl methylbenzoate, α-methyl styrene, maleimide, vinylpyridine, vinylpyrrolidone,vinylcarbazole, combinations of these, or the like.

In some embodiments, the repeating unit of the hydrocarbon structurealso has either a monocyclic or a polycyclic hydrocarbon structuresubstituted into it, or the monocyclic or polycyclic hydrocarbonstructure is the repeating unit, in order to form an alicyclichydrocarbon structure. Specific examples of monocyclic structures insome embodiments include bicycloalkane, tricycloalkane,tetracycloalkane, cyclopentane, cyclohexane, or the like. Specificexamples of polycyclic structures in some embodiments includeadamantane, norbornane, isobornane, tricyclodecane, tetracycododecane,or the like.

The group which will decompose, otherwise known as a leaving group or,in some embodiments in which the PAC is a photoacid generator, an acidlabile group, is attached to the hydrocarbon structure so that, it willreact with the acids/bases/free radicals generated by the PACs duringexposure. In some embodiments, the group which will decompose is acarboxylic acid group, a fluorinated alcohol group, a phenolic alcoholgroup, a sulfonic group, a sulfonamide group, a sulfonylimido group, an(alkylsulfonyl) (alkylcarbonyl)methylene group, an(alkylsulfonyl)(alkyl-carbonyl)imido group, abis(alkylcarbonyl)methylene group, a bis(alkylcarbonyl)imido group, abis(alkylsylfonyl)methylene group, a bis(alkylsulfonyl)imido group, atris(alkylcarbonyl methylene group, a tris(alkylsulfonyl)methylenegroup, combinations of these, or the like. Specific groups that are usedfor the fluorinated alcohol group include fluorinated hydroxyalkylgroups, such as a hexafluoroisopropanol group in some embodiments.Specific groups that are used for the carboxylic acid group includeacrylic acid groups, methacrylic acid groups, or the like.

In some embodiments, the polymer resin also includes other groupsattached to the hydrocarbon structure that help to improve a variety ofproperties of the polymerizable resin. For example, inclusion of alactone group to the hydrocarbon structure assists to reduce the amountof line edge roughness after the photoresist has been developed, therebyhelping to reduce the number of defects that occur during development.In some embodiments, the lactone groups include rings having five toseven members, although any suitable lactone structure may alternativelybe used for the lactone group.

In some embodiments, the polymer resin includes groups that can assistin increasing the adhesiveness of the photoresist layer 15 to underlyingstructures (e.g., substrate 10). Polar groups may be used to helpincrease the adhesiveness. Suitable polar groups include hydroxylgroups, cyano groups, or the like, although any suitable polar groupmay, alternatively, be used.

Optionally, the polymer resin includes one or more alicyclic hydrocarbonstructures that do not also contain a group which will decompose in someembodiments. In some embodiments, the hydrocarbon structure that doesnot contain a group which will decompose includes structures such as1-adamantyl(meth)acrylate, tricyclodecanyl (meth)acrylate, cyclohexayl(methacrylate), combinations of these, or the like.

Additionally, some embodiments of the photoresist include one or morephotoactive compounds (PACs). The PACs are photoactive components, suchas photoacid generators, photobase generators, free-radical generators,or the like. The PACs may be positive-acting or negative-acting. In someembodiments in which the PACs are a photoacid generator, the PACsinclude halogenated triazines, onium salts, diazonium salts, aromaticdiazonium salts, phosphonium salts, sulfonium salts, iodonium salts,imide sulfonate, oxime sulfonate, diazodisulfone, disulfone,o-nitrobenzylsulfonate, sulfonated esters, halogenated sulfonyloxydicarboximides, diazodisulfones, α-cyanooxyamine-sulfonates,imidesulfonates, ketodiazosulfones, sulfonyldiazoesters,1,2-di(arylsulfonyl)hydrazines, nitrobenzyl esters, and the s-triazinederivatives, combinations of these, or the like.

Specific examples of photoacid generators includeα-(trifluoromethylsulfonyloxy)-bicyclo[2.2.1]hept-5-ene-2,3-dicarb-o-ximide(MDT), N-hydroxy-naphthalimide (DDSN), benzoin tosylate,t-butylphenyl-α-(p-toluenesulfonyloxy)-acetate andt-butyl-α-(p-toluenesulfonyloxy)-acetate, triarylsulfonium anddiaryliodonium hexafluoroantimonates, hexafluoroarsenates,trifluoromethanesulfonates, iodonium perfluorooctanesulfonate,N-camphorsulfonyloxynaphthalimide,N-pentafluorophenylsulfonyloxynaphthalimide, ionic iodonium sulfonatessuch as diaryl iodonium (alkyl or aryl)sulfonate andbis-(di-t-butylphenyl)iodonium camphanylsulfonate,perfluoroalkanesulfonates such as perfluoropentanesulfonate,perfluorooctanesulfonate, perfluoromethanesulfonate, aryl (e.g., phenylor benzyl)triflates such as triphenylsulfonium triflate orbis-(t-butylphenyl)iodonium triflate; pyrogallol derivatives (e.g.,trimesylate of pyrogallol), trifluoromethanesulfonate esters ofhydroxyimides, α,α′-bis-sulfonyl-diazomethanes, sulfonate esters ofnitro-substituted benzyl alcohols, naphthoquinone-4-diazides, alkyldisulfones, or the like.

In some embodiments in which the PACs are free-radical generators, thePACs include n-phenylglycine; aromatic ketones, including benzophenone,N,N′-tetramethyl-4,4′-diaminobenzophenone,N,N′-tetraethyl-4,4′-diaminobenzophenone,4-methoxy-4′-dimethylaminobenzo-phenone,3,3′-dimethyl-4-methoxybenzophenone,p,p′-bis(dimethylamino)benzo-phenone,p,p′-bis(diethylamino)-benzophenone; anthraquinone,2-ethylanthraquinone; naphthaquinone; and phenanthraquinone; benzoinsincluding benzoin, benzoinmethylether, benzoinisopropylether,benzoin-n-butylether, benzoin-phenylether, methylbenzoin andethylbenzoin; benzyl derivatives, including dibenzyl,benzyldiphenyldisulfide, and benzyldimethylketal; acridine derivatives,including 9-phenylacridine, and 1,7-bis(9-acridinyl)heptane;thioxanthones, including 2-chlorothioxanthone, 2-methylthioxanthone,2,4-diethylthioxanthone, 2,4-dimethylthioxanthone, and2-isopropylthioxanthone; acetophenones, including1,1-dichloroacetophenone, p-t-butyldichloro-acetophenone,2,2-diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, and2,2-dichloro-4-phenoxyacetophenone; 2,4,5-triarylimidazole dimers,including 2-(o-chlorophenyl)-4,5-diphenylimidazole dimer,2-(o-chlorophenyl)-4,5-di-(m-methoxyphenyl imidazole dimer,2-(o-fluorophenyl)-4,5-diphenylimidazole dimer,2-(o-methoxyphenyl)-4,5-diphenylimidazole dimer,2-(p-methoxyphenyl)-4,5-diphenylimidazole dimer,2,4-di(p-methoxyphenyl)-5-phenylimidazole dimer,2-(2,4-dimethoxyphenyl)-4,5-diphenylimidazole dimer and2-(p-methylmercaptophenyl)-4,5-diphenylimidazole dimmer; combinations ofthese, or the like.

In some embodiments in which the PACs are photobase generators, the PACsincludes quaternary ammonium dithiocarbamates, α aminoketones,oxime-urethane containing molecules such as dibenzophenoneoximehexamethylene diurethan, ammonium tetraorganylborate salts, andN-(2-nitrobenzyloxycarbonyl)cyclic amines, combinations of these, or thelike.

As one of ordinary skill in the art will recognize, the chemicalcompounds listed herein are merely intended as illustrated examples ofthe PACs and are not intended to limit the embodiments to only thosePACs specifically described. Rather, any suitable PAC may be used, andall such PACs are fully intended to be included within the scope of thepresent embodiments.

In some embodiments, a cross-linking agent is added to the photoresist.The cross-linking agent reacts with one group from one of thehydrocarbon structures in the polymer resin and also reacts with asecond group from a separate one of the hydrocarbon structures in orderto cross-link and bond the two hydrocarbon structures together. Thisbonding and cross-linking increases the molecular weight of the polymerproducts of the cross-linking reaction and increases the overall linkingdensity of the photoresist. Such an increase in density and linkingdensity helps to improve the resist pattern.

In some embodiments the cross-linking agent has the following structure:

wherein C is carbon, n ranges from 1 to 15; A and B independentlyinclude a hydrogen atom, a hydroxyl group, a halide, an aromatic carbonring, or a straight or cyclic alkyl, alkoxyl/fluoro, alkyl/fluoroalkoxylchain having a carbon number of between 1 and 12, and each carbon Ccontains A and B; a first terminal carbon C at a first end of a carbon Cchain includes X and a second terminal carbon C at a second end of thecarbon chain includes Y, wherein X and Y independently include an aminegroup, a thiol group, a hydroxyl group, an isopropyl alcohol group, oran isopropyl amine group, except when n=1 then X and Y are bonded to thesame carbon C. Specific examples of materials that may be used as thecross-linking agent include the following:

Alternatively, instead of or in addition to the cross-linking agentbeing added to the photoresist composition, a coupling reagent is addedin some embodiments, in which the coupling reagent is added in additionto the cross-linking agent. The coupling reagent assists thecross-linking reaction by reacting with the groups on the hydrocarbonstructure in the polymer resin before the cross-linking reagent,allowing for a reduction in the reaction energy of the cross-linkingreaction and an increase in the rate of reaction. The bonded couplingreagent then reacts with the cross-linking agent, thereby coupling thecross-linking agent to the polymer resin.

Alternatively, in some embodiments in which the coupling reagent isadded to the photoresist without the cross-linking agent, the couplingreagent is used to couple one group from one of the hydrocarbonstructures in the polymer resin to a second group from a separate one ofthe hydrocarbon structures in order to cross-link and bond the twopolymers together. However, in such an embodiment the coupling reagent,unlike the cross-linking agent, does not remain as part of the polymer,and only assists in bonding one hydrocarbon structure directly toanother hydrocarbon structure.

In some embodiments, the coupling reagent has the following structure:

where R is a carbon atom, a nitrogen atom, a sulfur atom, or an oxygenatom; M includes a chlorine atom, a bromine atom, an iodine atom, —NO₂;—SO₃—; —H—; —CN; —NCO, —OCN; —CO₂—; —OH; —OR*, —OC(O)CR*; —SR,—SO2N(R*)₂; —SO₂R*; SOR; —OC(O)R*; —C(O)OR*; —C(O)R*; —Si(OR*)₃;—Si(R*)₃; epoxy groups, or the like; and R* is a substituted orunsubstituted C1-C12 alkyl, C1-C12 aryl, C1-C12 aralkyl, or the like.Specific examples of materials used as the coupling reagent in someembodiments include the following:

In some embodiments, the photoresist includes a protective polymer thatforms a protective layer 20 when applied to a layer to be patterned orsubstrate 10. In some embodiments, the protective polymer hasfluorocarbon pendant groups. In an embodiment, a main chain of thepolymer having fluorocarbon pendant groups is a polyhydroxystyrene, apolyacrylate, or a polymer formed from a 1 to 10 carbon monomer. In anembodiment, the polymer having fluorocarbon pendant groups includes fromabout 0.1 wt. % to about 10 wt. % of one or more polar functional groupsselected from the group consisting —OH, —NH₃, —NH₂, and —SO₃ based onthe total weight of the polymer having fluorocarbon groups. In anembodiment, the polymer having fluorocarbon pendant groups includes fromabout 0.1 wt. % to about 10 wt. % of the fluorocarbon pendant groupsbased on the total weight of the polymer having fluorocarbon groups. Inan embodiment, the fluorocarbon pendant groups are attached to a polymermain chain via a linking unit R1 of at least one selected from the groupconsisting of 1-9 carbon unbranched, branched, cyclic, noncylic,saturated, or unsaturated hydrocarbon with optional halogensubstituents; —S—; —P—; —P(O₂); —C(═O)S—; —C(═O)O—; —O—; —N—; —C(═O)N—;—SO₂O—; —SO₂S—; —SO—; —SO₂—; and —C(═O)—. In an embodiment, thefluorocarbon pendant group is selected from the group consisting ofC_(x)F_(y), where 1≤x≤9 and 3≤y≤12; and —(C(CF₃)₂OH)—. Examples ofC_(x)F_(y) units attached to the polymer chain via a linking unit R1according to embodiments of the disclosure are shown in FIG. 8. Asshown, in some embodiments, C_(x)F_(y) is one or more selected from thegroup consisting of —C₂F₅, —CH₂CH₂C₃F₇, —(C(CF₃)₂OH), —C(═O)OC₄F₉,—CH₂OC₄F₉, and —C(═O)O(C(CF₃)₂OH). In some embodiments, the amount ofprotective polymer having fluorocarbon pendant groups in thephotoresist/protective polymer mixture ranges from about 1 wt. % toabout 10 wt. % based on the total weight of the photoresist/protectivepolymer mixture. In some embodiments, the protective polymer havingfluorocarbon pendant groups has a weight average molecular weight ofabout 3000 to about 15,000. In some embodiments, the protective polymerhaving fluorocarbon pendant groups has a weight average molecular weightof about 6000 to about 11,000.

The individual components of the photoresist and the protective polymerare placed into a solvent in order to aid in the mixing and dispensingof the photoresist. To aid in the mixing and dispensing of thephotoresist, the solvent is chosen at least in part based upon thematerials chosen for the polymer resins as well as the PACs. In someembodiments, the solvent is chosen such that the polymer resins(photoresist polymer and protective polymer) and the PACs can be evenlydissolved into the solvent and dispensed upon the layer to be patterned.

In some embodiments, the solvent is an organic solvent, and includes oneor more of any suitable solvent such as ketones, alcohols, polyalcohols,ethers, glycol ethers, cyclic ethers, aromatic hydrocarbons, esters,propionates, lactates, lactic esters, alkylene glycol monoalkyl ethers,alkyl lactates, alkyl alkoxypropionates, cyclic lactones, monoketonecompounds that contain a ring, alkylene carbonates, alkyl alkoxyacetate,alkyl pyruvates, lactate esters, ethylene glycol alkyl ether acetates,diethylene glycols, propylene glycol alkyl ether acetates, alkyleneglycol alkyl ether esters, alkylene glycol monoalkyl esters, or thelike.

Specific examples of materials that may be used as the solvent for thephotoresist include, acetone, methanol, ethanol, toluene, xylene,4-hydroxy-4-methyl-2-pentatone, tetrahydrofuran, methyl ethyl ketone,cyclohexanone, methyl isoamyl ketone, 2-heptanone, ethylene glycol,ethylene glycol monoacetate, ethylene glycol dimethyl ether, ethyleneglycol dimethyl ether, ethylene glycol methylethyl ether, ethyleneglycol monoethyl ether, methyl cellosolve acetate, ethyl cellosolveacetate, diethylene glycol, diethylene glycol monoacetate, diethyleneglycol monomethyl ether, diethylene glycol diethyl ether, diethyleneglycol dimethyl ether, diethylene glycol ethylmethyl ether,diethethylene glycol monoethyl ether, diethylene glycol monobutyl ether,ethyl 2-hydroxypropionate, methyl 2-hydroxy-2-methylpropionate, ethyl2-hydroxy-2-methylpropionate, ethyl ethoxyacetate, ethyl hydroxyacetate,methyl 2-hydroxy-2-methylbutanate, methyl 3-methoxypropionate, ethyl3-methoxypropionate, methyl 3-ethoxypropionate, ethyl3-ethoxypropionate, methyl acetate, ethyl acetate, propyl acetate, butylacetate, methyl lactate, ethyl lactate, propyl lactate, butyl lactate,propylene glycol, propylene glycol monoacetate, propylene glycolmonoethyl ether acetate, propylene glycol monomethyl ether acetate,propylene glycol monopropyl methyl ether acetate, propylene glycolmonobutyl ether acetate, propylene glycol monobutyl ether acetate,propylene glycol monomethyl ether propionate, propylene glycol monoethylether propionate, propylene glycol methyl ether acetate, propyleneglycol ethyl ether acetate, ethylene glycol monomethyl ether acetate,ethylene glycol monoethyl ether acetate, propylene glycol monomethylether, propylene glycol monoethyl ether, propylene glycol monopropylether, propylene glycol monobutyl ether, ethylene glycol monomethylether, ethylene glycol monoethyl ether, ethyl 3-ethoxypropionate, methyl3-methoxypropionate, methyl 3-ethoxypropionate, and ethyl3-methoxypropionate, β-propiolactone, β-butyrolactone, γ-butyrolactone,α-methyl-γ-butyrolactone, β-methyl-γ-butyrolactone, γ-valerolactone,γ-caprolactone, γ-octanoic lactone, α-hydroxy-γ-butyrolactone,2-butanone, 3-methylbutanone, pinacolone, 2-pentanone, 3-pentanone,4-methyl-2-pentanone, 2-methyl-3-pentanone, 4,4-dimethyl-2-pentanone,2,4-dimethyl-3-pentanone, 2,2,4,4-tetramethyl-3-pentanone, 2-hexanone,3-hexanone, 5-methyl-3-hexanone, 2-heptanone, 3-heptanone, 4-heptanone,2-methyl-3-heptanone, 5-methyl-3-heptanone, 2,6-dimethyl-4-heptanone,2-octanone, 3-octanone, 2-nonanone, 3-nonanone, 5-nonanone, 2-decanone,3-decanone, 4-decanone, 5-hexene-2-one, 3-pentene-2-one, cyclopentanone,2-methylcyclopentanone, 3-methylcyclopentanone,2,2-dimethylcyclopentanone, 2,4,4-trimethylcyclopentanone,cyclohexanone, 3-methylcyclohexanone, 4-methylcyclohexanone,4-ethylcyclohexanone, 2,2-dimethylcyclohexanone,2,6-dimethylcyclohexanone, 2,2,6-trimethylcyclohexanone, cycloheptanone,2-methylcycloheptanone, 3-methylcycloheptanone, propylene carbonate,vinylene carbonate, ethylene carbonate, butylene carbonate,acetate-2-methoxyethyl, acetate-2-ethoxyethyl,acetate-2-(2-ethoxyethoxy)ethyl, acetate-3-methoxy-3-methylbutyl,acetate-1-methoxy-2-propyl, dipropylene glycol, monomethylether,monoethylether, monopropylether, monobutylether, monophenylether,dipropylene glycol monoacetate, dioxane, methyl pyruvate, ethylpyruvate, propyl pyruvate, methyl methoxypropionate, ethylethoxypropionate, n-methylpyrrolidone (NMP), 2-methoxyethyl ether(diglyme), ethylene glycol monomethyl ether, propylene glycol monomethylether, methyl propionate, ethyl propionate, ethyl ethoxy propionate,methylethyl ketone, cyclohexanone, 2-heptanone, cyclopentanone,cyclohexanone, ethyl 3-ethoxypropionate, propylene glycol methyl etheracetate (PGMEA), methylene cellosolve, 2-ethoxyethanol,N-methylformamide, N,N-dimethylformamide, N-methylformanilide,N-methylacetamide, N,N-dimethylacetamide, dimethylsulfoxide, benzylethyl ether, dihexyl ether, acetonylacetone, isophorone, caproic acid,caprylic acid, 1-octanol, 1-nonanol, benzyl alcohol, benzyl acetate,ethyl benzoate, diethyl oxalate, diethyl maleate, phenyl cellosolveacetate, or the like.

As one of ordinary skill in the art will recognize, the materials listedand described above as examples of materials that may be used for thesolvent component of the photoresist are merely illustrative and are notintended to limit the embodiments. Rather, any suitable materials thatdissolve the polymer resin and the PACs may be used to help mix andapply the photoresist. All such materials are fully intended to beincluded within the scope of the embodiments.

Additionally, while individual ones of the above described materials maybe used as the solvent for the photoresist and protective polymer, inother embodiments more than one of the above described materials areused. For example, in some embodiments, the solvent includes acombination mixture of two or more of the materials described. All suchcombinations are fully intended to be included within the scope of theembodiments.

In addition to the polymer resins, the PACs, the solvents, thecross-linking agent, and the coupling reagent, some embodiments of thephotoresist also includes a number of other additives that assist thephotoresist to obtain high resolution. For example, some embodiments ofthe photoresist also includes surfactants in order to help improve theability of the photoresist to coat the surface on which it is applied.In some embodiments, the surfactants include nonionic surfactants,polymers having fluorinated aliphatic groups, surfactants that containat least one fluorine atom and/or at least one silicon atom,polyoxyethylene alkyl ethers, polyoxyethylene alkyl aryl ethers,polyoxyethylene-polyoxypropylene block copolymers, sorbitan fatty acidesters, and polyoxyethylene sorbitan fatty acid esters.

Specific examples of materials used as surfactants in some embodimentsinclude polyoxyethylene lauryl ether, polyoxyethylene stearyl ether,polyoxyethylene cetyl ether, polyoxyethylene oleyl ether,polyoxyethylene octyl phenol ether, polyoxyethylene nonyl phenol ether,sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate,sorbitan monooleate, sorbitan trioleate, sorbitan tristearate,polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitanmonopalmitate, polyoxyethylene sorbitan monostearate, polyoxyethylenesorbitan trioleate, polyoxyethylene sorbitan tristearate, polyethyleneglycol distearate, polyethylene glycol dilaurate, polyethylene glycoldilaurate, polyethylene glycol, polypropylene glycol,polyoxyethylenestearyl ether, polyoxyethylene cetyl ether, fluorinecontaining cationic surfactants, fluorine containing nonionicsurfactants, fluorine containing anionic surfactants, cationicsurfactants and anionic surfactants, polyethylene glycol, polypropyleneglycol, polyoxyethylene cetyl ether, combinations thereof, or the like.

Another additive added to some embodiments of the photoresist is aquencher, which inhibits diffusion of the generated acids/bases/freeradicals within the photoresist. The quencher improves the resistpattern configuration as well as the stability of the photoresist overtime. In an embodiment, the quencher is an amine, such as a second loweraliphatic amine, a tertiary lower aliphatic amine, or the like. Specificexamples of amines include trimethylamine, diethylamine, triethylamine,di-n-propylamine, tri-n-propylamine, tripentylamine, diethanolamine, andtriethanolamine, alkanolamine, combinations thereof, or the like.

In some embodiments, an organic acid is used as the quencher. Specificembodiments of organic acids include malonic acid, citric acid, malicacid, succinic acid, benzoic acid, salicylic acid; phosphorous oxo acidand its derivatives, such as phosphoric acid and derivatives thereofsuch as its esters, phosphoric acid di-n-butyl ester and phosphoric aciddiphenyl ester; phosphonic acid and derivatives thereof such as itsester, such as phosphonic acid dimethyl ester, phosphonic aciddi-n-butyl ester, phenylphosphonic acid, phosphonic acid diphenyl ester,and phosphonic acid dibenzyl ester; and phosphinic acid and derivativesthereof such as its esters, including phenylphosphinic acid.

Another additive added to some embodiments of the photoresist is astabilizer, which assists in preventing undesired diffusion of the acidsgenerated during exposure of the photoresist. In some embodiments, thestabilizer includes nitrogenous compounds, including aliphatic primary,secondary, and tertiary amines; cyclic amines, including piperidines,pyrrolidines, morpholines; aromatic heterocycles, including pyridines,pyrimidines, purines; imines, including diazabicycloundecene,guanidines, imides, amides, or the like. Alternatively, ammonium saltsare also be used for the stabilizer in some embodiments, includingammonium, primary, secondary, tertiary, and quaternary alkyl- andaryl-ammonium salts of alkoxides, including hydroxide, phenolates,carboxylates, aryl and alkyl sulfonates, sulfonamides, or the like.Other cationic nitrogenous compounds, including pyridinium salts andsalts of other heterocyclic nitrogenous compounds with anions, such asalkoxides, including hydroxide, phenolates, carboxylates, aryl and alkylsulfonates, sulfonamides, or the like, are used in some embodiments.

Another additive in some embodiments of the photoresist is a dissolutioninhibitor to help control dissolution of the photoresist duringdevelopment. In an embodiment bile-salt esters may be utilized as thedissolution inhibitor. Specific examples of dissolution inhibitors insome embodiments include cholic acid, deoxycholic acid, lithocholicacid, t-butyl deoxycholate, t-butyl lithocholate, and t-butyl-3-acetyllithocholate.

Another additive in some embodiments of the photoresist is aplasticizer. Plasticizers may be used to reduce delamination andcracking between the photoresist and underlying layers (e.g., the layerto be patterned). Plasticizers include monomeric, oligomeric, andpolymeric plasticizers, such as oligo- and polyethyleneglycol ethers,cycloaliphatic esters, and non-acid reactive steroidaly-derivedmaterials. Specific examples of materials used for the plasticizer insome embodiments include dioctyl phthalate, didodecyl phthalate,triethylene glycol dicaprylate, dimethyl glycol phthalate, tricresylphosphate, dioctyl adipate, dibutyl sebacate, triacetyl glycerine, orthe like.

A coloring agent is another additive included in some embodiments of thephotoresist. The coloring agent observers examine the photoresist andfind any defects that may need to be remedied prior to furtherprocessing. In some embodiments, the coloring agent is a triarylmethanedye or a fine particle organic pigment. Specific examples of materialsin some embodiments include crystal violet, methyl violet, ethyl violet,oil blue #603, Victoria Pure Blue BOH, malachite green, diamond green,phthalocyanine pigments, azo pigments, carbon black, titanium oxide,brilliant green dye (C. I. 42020), Victoria Pure Blue FGA (Linebrow),Victoria BO (Linebrow) (C. I. 42595), Victoria Blue BO (C. I. 44045),rhodamine 6G (C. I. 45160), benzophenone compounds, such as2,4-dihydroxybenzophenone and 2,2′,4,4′-tetrahydroxybenzophenone;salicylic acid compounds, such as phenyl salicylate and 4-t-butylphenylsalicylate; phenylacrylate compounds, such asethyl-2-cyano-3,3-diphenylacrylate, and2′-ethylhexyl-2-cyano-3,3-diphenylacrylate; benzotriazole compounds,such as 2-(2-hydroxy-5-methylphenyl)-2H-benzotriazole, and2-(3-t-butyl-2-hydroxy-5-methylphenyl)-5-chloro-2H-benzotriazole;coumarin compounds, such as 4-methyl-7-diethylamino-1-benzopyran-2-one;thioxanthone compounds, such as diethylthioxanthone; stilbene compounds,naphthalic acid compounds, azo dyes, phthalocyanine blue, phthalocyaninegreen, iodine green, Victoria blue, crystal violet, titanium oxide,naphthalene black, Photopia methyl violet, bromphenol blue andbromcresol green; laser dyes, such as Rhodamine G6, Coumarin 500, DCM(4-(dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4H pyran)),Kiton Red 620, Pyrromethene 580, or the like. Additionally, one or morecoloring agents may be used in combination to provide the desiredcoloring.

Adhesion additives are added to some embodiments of the photoresist topromote adhesion between the photoresist and an underlying layer uponwhich the photoresist has been applied (e.g., the layer to bepatterned). In some embodiments, the adhesion additives include a silanecompound with at least one reactive substituent such as a carboxylgroup, a methacryloyl group, an isocyanate group and/or an epoxy group.Specific examples of the adhesion components include trimethoxysilylbenzoic acid, γ-methacryloxypropyl trimethoxy silane,vinyltriacetoxysilane, vinyltrimethoxysilane, γ-isocyanatepropyltriethoxy silane, γ-glycidoxypropyl trimethoxy silane,β-(3,4-epoxycyclohexyl)ethyl trimethoxy silane, benzimidazoles andpolybenzimidazoles, a lower hydroxyalkyl substituted pyridinederivative, a nitrogen heterocyclic compound, urea, thiourea, anorganophosphorus compound, 8-oxyquinoline, 4-hydroxypteridine andderivatives, 1,10-phenanthroline and derivatives, 2,2′-bipyridine andderivatives, benzotriazoles, organophosphorus compounds,phenylenediamine compounds, 2-amino-1-phenylethanol,N-phenylethanolamine, N-ethyldiethanolamine, N-ethylethanolamine andderivatives, benzothiazole, and a benzothiazoleamine salt having acyclohexyl ring and a morpholine ring,3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane,3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane,3-methacryloyloxypropyltrimethoxysilane, vinyl trimethoxysilane,combinations thereof, or the like.

Surface leveling agents are added to some embodiments of the photoresistto assist a top surface of the photoresist to be level, so thatimpinging light will not be adversely modified by an unlevel surface. Insome embodiments, surface leveling agents include fluoroaliphaticesters, hydroxyl terminated fluorinated polyethers, fluorinated ethyleneglycol polymers, silicones, acrylic polymer leveling agents,combinations thereof, or the like.

Some embodiments of the photoresist include metal oxide nanoparticles.In some embodiments, the photoresist includes one or more metal oxidesnanoparticles selected from the group consisting of titanium dioxide,zinc oxide, zirconium dioxide, nickel oxide, cobalt oxide, manganeseoxide, copper oxides, iron oxides, strontium titanate, tungsten oxides,vanadium oxides, chromium oxides, tin oxides, hafnium oxide, indiumoxide, cadmium oxide, molybdenum oxide, tantalum oxides, niobium oxide,aluminum oxide, and combinations thereof. As used herein, nanoparticlesare particles having an average particle size between 1 and 10 nm. Insome embodiments the metal oxide nanoparticles have an average particlesize between 2 and 5 nm. In some embodiments, the amount of metal oxidenanoparticles in the photoresist composition ranges from about 1 wt. %to about 10 wt. % based on the total weight of the photoresistcomposition.

In some embodiments, the metal oxide nanoparticles are complexed withcarboxylic acid or sulfonic acid ligands. For example, in someembodiments zirconium oxide or hafnium oxide nanoparticles are complexedwith methacrylic acid forming hafnium methacrylic acid (HfMAA) orzirconium oxide (ZrMAA). In some embodiments, the HfMAA or ZrMAA aredissolved at about a 5 wt. % to about 10 wt. % weight range in a coatingsolvent, such as propylene glycol methyl ether acetate (PGMEA). In someembodiments, about 1 wt. % to about 10 wt. % of a photoactive compound(PAC) based on the total weight of the photoresist composition to form ametal oxide resist. In some embodiments, the protective polymer is addedto the metal oxide resist.

In some embodiments, the polymer resins (photoresist resin andprotective resin) and the PACs, along with any desired additives orother agents, are added to the solvent for application. Once added, themixture is then mixed in order to achieve a homogenous compositionthroughout the photoresist to ensure that there are no defects caused byuneven mixing or nonhomogenous composition of the photoresist. Oncemixed together, the photoresist may either be stored prior to its usageor used immediately.

In some embodiments, a protective polymer composition is preparedseparate from the photoresist composition, and applied separately to thephotoresist coated substrate, as shown in FIGS. 3A-3D. In suchembodiments, the protective polymer is any polymer selected from theprotective polymers previously disclosed herein having fluorocarbonpendant groups. In an embodiment, a main chain of the polymer havingfluorocarbon pendant groups is a polyhydroxystyrene, a polyacrylate, ora polymer formed from a 1 to 10 carbon monomer. In an embodiment, thepolymer having fluorocarbon pendant groups includes from about 0.1 wt. %to about 10 wt. % of one or more polar functional groups selected fromthe group consisting —OH, —NH₃, —NH₂, and —SO₃ based on the total weightof the polymer having fluorocarbon groups. In an embodiment, the polymerhaving fluorocarbon pendant groups includes from about 0.1 wt. % toabout 10 wt. % of the fluorocarbon pendant groups based on the totalweight of the polymer having fluorocarbon groups. In an embodiment, thefluorocarbon pendant groups are attached to a polymer main chain via alinking unit R1 of at least one selected from the group consisting of1-9 carbon unbranched, branched, cyclic, noncylic, saturated, orunsaturated hydrocarbon with optional halogen substituents; —S—; —P—;—P(O₂); —C(═O)S—; —C(═O)O—; —O—; —N—; —C(═O)N—; —SO₂O—; —SO₂S—; —SO—;—SO₂—; and —C(═O)—. In an embodiment, the fluorocarbon pendant group isselected from the group consisting of C_(x)F_(y), where 1≤x≤9 and3≤y≤12; and —(C(CF₃)₂OH)—. Examples of C_(x)F_(y) units attached to thepolymer chain via a linking unit R1 according to embodiments of thedisclosure are shown in FIG. 8. As shown, in some embodiments,C_(x)F_(y) is one or more selected from the group consisting of —C₂F₅,—CH₂CH₂C₃F₇, —(C(CF₃)₂OH), —C(═O)OC₄F₉, —CH₂OC₄F₉, and—C(═O)O(C(CF₃)₂OH). In an embodiment, the protective polymer havingfluorocarbon pendant groups has a weight average molecular weight ofabout 3000 to about 15,000.

The protective polymer is placed into a solvent in order to aid indispensing of the protective polymer. To aid in the mixing anddispensing of the protective polymer, the solvent is chosen at least inpart based upon the materials chosen for the polymer resins as well asthe PACs. In some embodiments, the solvent is an organic solvent, andincludes one or more of any suitable solvent such as ketones, alcohols,polyalcohols, ethers, glycol ethers, cyclic ethers, aromatichydrocarbons, esters, propionates, lactates, lactic esters, alkyleneglycol monoalkyl ethers, alkyl lactates, alkyl alkoxypropionates, cycliclactones, monoketone compounds that contain a ring, alkylene carbonates,alkyl alkoxyacetate, alkyl pyruvates, lactate esters, ethylene glycolalkyl ether acetates, diethylene glycols, propylene glycol alkyl etheracetates, alkylene glycol alkyl ether esters, alkylene glycol monoalkylesters, or the like.

Specific examples of materials that may be used as the solvent for theprotective polymer include, acetone, methanol, ethanol, toluene, xylene,4-hydroxy-4-methyl-2-pentatone, tetrahydrofuran, methyl ethyl ketone,cyclohexanone, methyl isoamyl ketone, 2-heptanone, ethylene glycol,ethylene glycol monoacetate, ethylene glycol dimethyl ether, ethyleneglycol dimethyl ether, ethylene glycol methylethyl ether, ethyleneglycol monoethyl ether, methyl cellosolve acetate, ethyl cellosolveacetate, diethylene glycol, diethylene glycol monoacetate, diethyleneglycol monomethyl ether, diethylene glycol diethyl ether, diethyleneglycol dimethyl ether, diethylene glycol ethylmethyl ether,diethethylene glycol monoethyl ether, diethylene glycol monobutyl ether,ethyl 2-hydroxypropionate, methyl 2-hydroxy-2-methylpropionate, ethyl2-hydroxy-2-methylpropionate, ethyl ethoxyacetate, ethyl hydroxyacetate,methyl 2-hydroxy-2-methylbutanate, methyl 3-methoxypropionate, ethyl3-methoxypropionate, methyl 3-ethoxypropionate, ethyl3-ethoxypropionate, methyl acetate, ethyl acetate, propyl acetate, butylacetate, methyl lactate, ethyl lactate, propyl lactate, butyl lactate,propylene glycol, propylene glycol monoacetate, propylene glycolmonoethyl ether acetate, propylene glycol monomethyl ether acetate,propylene glycol monopropyl methyl ether acetate, propylene glycolmonobutyl ether acetate, propylene glycol monobutyl ether acetate,propylene glycol monomethyl ether propionate, propylene glycol monoethylether propionate, propylene glycol methyl ether acetate, propyleneglycol ethyl ether acetate, ethylene glycol monomethyl ether acetate,ethylene glycol monoethyl ether acetate, propylene glycol monomethylether, propylene glycol monoethyl ether, propylene glycol monopropylether, propylene glycol monobutyl ether, ethylene glycol monomethylether, ethylene glycol monoethyl ether, ethyl 3-ethoxypropionate, methyl3-methoxypropionate, methyl 3-ethoxypropionate, and ethyl3-methoxypropionate, β-propiolactone, β-butyrolactone, γ-butyrolactone,α-methyl-γ-butyrolactone, β-methyl-γ-butyrolactone, γ-valerolactone,γ-caprolactone, γ-octanoic lactone, α-hydroxy-γ-butyrolactone,2-butanone, 3-methylbutanone, pinacolone, 2-pentanone, 3-pentanone,4-methyl-2-pentanone, 2-methyl-3-pentanone, 4,4-dimethyl-2-pentanone,2,4-dimethyl-3-pentanone, 2,2,4,4-tetramethyl-3-pentanone, 2-hexanone,3-hexanone, 5-methyl-3-hexanone, 2-heptanone, 3-heptanone, 4-heptanone,2-methyl-3-heptanone, 5-methyl-3-heptanone, 2,6-dimethyl-4-heptanone,2-octanone, 3-octanone, 2-nonanone, 3-nonanone, 5-nonanone, 2-decanone,3-decanone, 4-decanone, 5-hexene-2-one, 3-pentene-2-one, cyclopentanone,2-methylcyclopentanone, 3-methylcyclopentanone,2,2-dimethylcyclopentanone, 2,4,4-trimethylcyclopentanone,cyclohexanone, 3-methylcyclohexanone, 4-methylcyclohexanone,4-ethylcyclohexanone, 2,2-dimethylcyclohexanone,2,6-dimethylcyclohexanone, 2,2,6-trimethylcyclohexanone, cycloheptanone,2-methylcycloheptanone, 3-methylcycloheptanone, propylene carbonate,vinylene carbonate, ethylene carbonate, butylene carbonate,acetate-2-methoxyethyl, acetate-2-ethoxyethyl,acetate-2-(2-ethoxyethoxy)ethyl, acetate-3-methoxy-3-methylbutyl,acetate-1-methoxy-2-propyl, dipropylene glycol, monomethylether,monoethylether, monopropylether, monobutylether, monophenylether,dipropylene glycol monoacetate, dioxane, methyl pyruvate, ethylpyruvate, propyl pyruvate, methyl methoxypropionate, ethylethoxypropionate, n-methylpyrrolidone (NMP), 2-methoxyethyl ether(diglyme), ethylene glycol monomethyl ether, propylene glycol monomethylether, methyl propionate, ethyl propionate, ethyl ethoxy propionate,methylethyl ketone, cyclohexanone, 2-heptanone, cyclopentanone,cyclohexanone, ethyl 3-ethoxypropionate, propylene glycol methyl etheracetate (PGMEA), methylene cellosolve, 2-ethoxyethanol,N-methylformamide, N,N-dimethylformamide, N-methylformanilide,N-methylacetamide, N,N-dimethylacetamide, dimethylsulfoxide, benzylethyl ether, dihexyl ether, acetonylacetone, isophorone, caproic acid,caprylic acid, 1-octanol, 1-nonanol, benzyl alcohol, benzyl acetate,ethyl benzoate, diethyl oxalate, diethyl maleate, phenyl cellosolveacetate, or the like.

As one of ordinary skill in the art will recognize, the materials listedand described above as examples of materials that may be used for thesolvent of the protective polymer are merely illustrative and are notintended to limit the embodiments. Rather, any suitable materials thatdissolve the protective polymer resin to help mix and apply theprotective polymer. All such materials are fully intended to be includedwithin the scope of the embodiments.

Once ready, the photoresist/protective polymer composition is appliedonto the layer to be patterned, as shown in FIG. 2A, such as thesubstrate 10 to form a photoresist layer 15 and protective layer, asshown in FIG. 2B. In some embodiments, the photoresist/protectivepolymer composition is applied using a process such as a spin-on coatingprocess. In other embodiments, a dip coating method, an air-knifecoating method, a curtain coating method, a wire-bar coating method, agravure coating method, a lamination method, an extrusion coatingmethod, combinations of these, or the like are used to coat thephotoresist on the substrate. In some embodiments, the photoresist layer15 thickness ranges from about 10 nm to about 300 nm, and the protectivelayer thickness ranges from about 0.1 nm to about 20 nm. In someembodiments, the thickness of the protective layer ranges from about 1nm to about 15 nm. In some embodiments, the contact angle of theprotective layer to water is greater than 75°.

After the photoresist layer 15 and protective layer 20 have been appliedto the substrate 10, a pre-bake of the photoresist layer is performed insome embodiments to cure and dry the photoresist prior to radiationexposure. The curing and drying of the photoresist layer 15 andprotective layer 20 removes the solvent component while leaving behindthe polymer resins, the PACs, the cross-linking agent, and the otherchosen additives. In some embodiments, the pre-baking is performed at atemperature suitable to evaporate the solvent, such as between about 50°C. and 250° C., although the precise temperature depends upon thematerials chosen for the photoresist. The pre-baking is performed for atime sufficient to cure and dry the photoresist layer and protectivelayer, such as between about 10 seconds to about 10 minutes.

In some embodiments, the photoresist layer 15 and protective layer 20are separately formed, as shown in FIGS. 3A-3D. In some embodiments,each of the photoresist and protective polymer are applied using aprocess such as a spin-on coating process, a dip coating method, anair-knife coating method, a curtain coating method, a wire-bar coatingmethod, a gravure coating method, a lamination method, an extrusioncoating method, combinations of these, or the like. Each of thephotoresist layer 15 and protective layer 20 are pre-baked afterapplication to cure and dry. In some embodiments, each pre-bakingoperation is performed at a temperature suitable to evaporate therespective solvents, such as between about 50° C. and 250° C., for aperiod of time between about 10 seconds to about 10 minutes.

FIG. 4 illustrates a selective exposure of the photoresist layer to forman exposed region 50 and an unexposed region 52. In some embodiments,the exposure to radiation is carried out by placing the photoresistcoated substrate in a photolithography tool. The photolithography toolincludes a photomask 30, optics, an exposure radiation source to providethe radiation 45 for exposure, and a movable stage for supporting andmoving the substrate under the exposure radiation.

In some embodiments, the radiation source (not shown) supplies radiation45, such as ultraviolet light, to the photoresist layer 15 in order toinduce a reaction of the PACs, which in turn reacts with the polymerresin to chemically alter those regions of the photoresist layer towhich the radiation 45 impinges. In some embodiments the radiation iselectromagnetic radiation, such as g-line (wavelength of about 436 nm),i-line (wavelength of about 365 nm), ultraviolet radiation, farultraviolet radiation, extreme ultraviolet, electron beams, or the like.In some embodiments, the radiation source is selected from the groupconsisting of a mercury vapor lamp, xenon lamp, carbon arc lamp, a KrFexcimer laser light (wavelength of 248 nm), an ArF excimer laser light(wavelength of 193 nm), an F₂ excimer laser light (wavelength of 157nm), or a CO₂ laser-excited Sn plasma (extreme ultraviolet, wavelengthof 13.5 nm).

In some embodiments, optics (not shown) are used in the photolithographytool to expand, reflect, or otherwise control the radiation before orafter the radiation 45 is patterned by the photomask 30. In someembodiments the optics include one or more lenses, mirrors, filters, andcombinations thereof to control the radiation 45 along its path.

In an embodiment, the patterned radiation 45 is extreme ultravioletlight having a 13.5 nm wavelength, the PAC is a photoacid generator, thegroup to be decomposed is a carboxylic acid group on the hydrocarbonstructure, and a cross linking agent is used. The patterned radiation 45impinges upon the photoacid generator, the photoacid generator absorbsthe impinging patterned radiation 45. This absorption initiates thephotoacid generator to generate a proton (e.g., a H⁺ atom) within thephotoresist layer 15. When the proton impacts the carboxylic acid groupon the hydrocarbon structure, the proton reacts with the carboxylic acidgroup, chemically altering the carboxylic acid group and altering theproperties of the polymer resin in general. The carboxylic acid groupthen reacts with the cross-linking agent to cross-link with otherpolymer resins within the exposed region of the photoresist layer 15.

In some embodiments, the exposure of the photoresist layer 15 uses animmersion lithography technique. In such a technique, an immersionmedium (not shown) is placed between the final optics and thephotoresist layer, and the exposure radiation 45 passes through theimmersion medium.

In some embodiments, the thickness of the protective layer 20 issufficiently thin so that the protective layer 20 does not adverselyaffect the exposure of the photoresist layer 15 to the radiation 45.

After the photoresist layer 15 has been exposed to the exposureradiation 45, a post-exposure baking is performed in some embodiments toassist in the generating, dispersing, and reacting of the acid/base/freeradical generated from the impingement of the radiation 45 upon the PACsduring the exposure. Such thermal assistance helps to create or enhancechemical reactions which generate chemical differences between theexposed region 50 and the unexposed region 52 within the photoresistlayer 15. These chemical differences also cause differences in thesolubility between the exposed region 50 and the unexposed region 52. Insome embodiments, the post-exposure baking occurs at temperaturesranging from about 50° C. to about 160° C. for a period of between about20 seconds and about 120 seconds.

After the selective radiation exposure and/or the post-exposure bakeoperation, the PAC in the photoresist produces an acid in someembodiments, and thus increases or decreases its solubility. Thesolubility may be increased for positive resist (i.e., the acid willcleave an acid cleavable polymer, resulting in the polymer becoming morehydrophilic) and decreased for negative resist (i.e., the acid willcatalyze an acid catalyzed crosslinkable polymer or cause a polymericpinnacle to undergo pincaol rearrangement, resulting in the polymerbecoming more hydrophobic). Thus, when an aqueous-based developer isused, the developer will dissolve the exposed portions of the positiveresist but not the exposed portions of the negative resist.

The inclusion of a cross-linking agent into the chemical reactions helpsthe components of the polymer resin (e.g., the individual polymers)react and bond with each other, increasing the molecular weight of thebonded polymer in some embodiments. In particular, an initial polymerhas a side chain with a carboxylic acid protected by one of the groupsto be removed/acid labile groups. The groups to be removed are removedin a de-protecting reaction, which is initiated by a proton H⁺ generatedby, e.g., the photoacid generator during either the exposure process orduring the post-exposure baking process. The H⁺ first removes the groupsto be removed/acid labile groups and another hydrogen atom may replacethe removed structure to form a de-protected polymer. Once de-protected,a cross-linking reaction occurs between two separate de-protectedpolymers that have undergone the de-protecting reaction and thecross-linking agent in a cross-linking reaction. In particular, hydrogenatoms within the carboxylic groups formed by the de-protecting reactionare removed and the oxygen atoms react with and bond with thecross-linking agent. This bonding of the cross-linking agent to twopolymers bonds the two polymers not only to the cross-linking agent butalso bonds the two polymers to each other through the cross-linkingagent, thereby forming a cross-linked polymer.

By increasing the molecular weight of the polymers through thecross-linking reaction, the new cross-linked polymer becomes lesssoluble in organic solvent negative resist developers.

Development is performed using a solvent. In some embodiments wherepositive tone development is desired, a positive tone developer such asa basic aqueous solution is used to remove regions 50 of the photoresistexposed to radiation. In some embodiments, the positive tone developer57 includes one or more selected from tetramethylammonium hydroxide(TMAH), tetrabutylammonium hydroxide, sodium hydroxide, potassiumhydroxide, sodium carbonate, sodium bicarbonate, sodium silicate, sodiummetasilicate, aqueous ammonia, monomethylamine, dimethylamine,trimethylamine, monoethylamine, diethylamine, triethylamine,monoisopropylamine, diisopropylamine, triisopropylamine, monobutylamine,dibutylamine, monoethanolamine, diethanolamine, triethanolamine,dimethylaminoethanol, diethylaminoethanol, ammonia, caustic soda,caustic potash, sodium metasilicate, potassium metasilicate, sodiumcarbonate, tetraethylammonium hydroxide, combinations of these, or thelike.

In some embodiments where negative tone development is desired, anorganic solvent or critical fluid is used to remove the unexposedregions 52 of the photoresist. In some embodiments, the negative tonedeveloper 57 includes one or more selected from hexane, heptane, octane,toluene, xylene, dichloromethane, chloroform, carbon tetrachloride,trichloroethylene, and like hydrocarbon solvents; critical carbondioxide, methanol, ethanol, propanol, butanol, and like alcoholsolvents; diethyl ether, dipropyl ether, dibutyl ether, ethyl vinylether, dioxane, propylene oxide, tetrahydrofuran, cellosolve, methylcellosolve, butyl cellosolve, methyl carbitol, diethylene glycolmonoethyl ether and like ether solvents; acetone, methyl ethyl ketone,methyl isobutyl ketone, isophorone, cyclohexanone and like ketonesolvents; methyl acetate, ethyl acetate, propyl acetate, butyl acetateand like ester solvents; pyridine, formamide, and N,N-dimethyl formamideor the like.

In some embodiments, the developer 57 is applied to the protective layerand photoresist layer 15 using a spin-on process. In the spin-onprocess, the developer 57 is applied to the protective layer 20 andphotoresist layer 15 by a dispenser 62 from above while the coatedsubstrate is rotated, as shown in FIG. 5. The developer 57 is selectedso that it both removes the protective layer 20 and the appropriateregion of photoresist layer 15. In the case of a positive resist, theexposed region 50 of the photoresist layer is removed, and in the caseof a negative resist the unexposed regions 52 of the photoresist layerare removed. In some embodiments the developer 57 is supplied at a rateof between about 5 ml/min and about 800 ml/min, while the coatedsubstrate 10 is rotated at a speed of between about 100 rpm and about2000 rpm. In some embodiments, the developer is at a temperature ofbetween about 10° C. and about 80° C. The development operationcontinues for between about 30 seconds to about 10 minutes in someembodiments.

While the spin-on operation is one suitable method for developing thephotoresist layer 15 after exposure, it is intended to be illustrativeand is not intended to limit the embodiment. Rather, any suitabledevelopment operations, including dip processes, puddle processes, andspray-on methods, may alternatively be used. All such developmentoperations are included within the scope of the embodiments.

During the development process, the developer 57 dissolves theprotective layer 20 and radiation unexposed regions 52 of thecross-linked negative resist, exposing the surface of the substrate 10,as shown in FIG. 6, and leaving behind well-defined exposed photoresistregions 50, in some embodiments.

After the developing operation S150, remaining developer is removed fromthe patterned photoresist covered substrate. The remaining developer isremoved using a spin-dry process in some embodiments, although anysuitable removal technique may be used. After the photoresist layer 15is developed, and the remaining developer is removed, additionalprocessing is performed while the patterned photoresist layer 50 is inplace. For example, an etching operation, using dry or wet etching, isperformed in some embodiments, to transfer the pattern 55 of thephotoresist layer 52 to the underlying substrate 10, forming recesses55′ as shown in FIG. 7. The substrate 10 has a different etch resistancethan the photoresist layer 15. In some embodiments, the etchant is moreselective to the substrate 10 than the photoresist layer 15.

In some embodiments, the substrate 10 and the photoresist layer 15contain at least one etching resistance molecule. In some embodiments,the etching resistant molecule includes a molecule having a low Onishinumber structure, a double bond, a triple bond, silicon, siliconnitride, titanium, titanium nitride, aluminum, aluminum oxide, siliconoxynitride, combinations thereof, or the like.

In some embodiments, a layer to be patterned 60 is disposed over thesubstrate prior to forming the photoresist layer 15, as shown in FIG. 9.In some embodiments, the layer to be patterned 60 is a metallizationlayer or a dielectric layer, such as a passivation layer, disposed overa metallization layer. In embodiments where the layer to be patterned 60is a metallization layer, the layer to be patterned 60 is formed of aconductive material using metallization processes, and metal depositiontechniques, including chemical vapor deposition, atomic layerdeposition, and physical vapor deposition (sputtering). Likewise, if thelayer to be patterned 60 is a dielectric layer, the layer to bepatterned 60 is formed by dielectric layer formation techniques,including thermal oxidation, chemical vapor deposition, atomic layerdeposition, and physical vapor deposition.

The photoresist layer 15 is subsequently selectively exposed to actinicradiation 45 to form exposed regions 50 and unexposed regions 52 in thephotoresist layer, as shown in FIG. 10, and described herein in relationto FIG. 4. In these embodiments, the photoresist is a positivephotoresist, wherein the solubility of the photoresist polymer in thedeveloper 57 increases in the exposed regions 50.

As shown in FIG. 11, the exposed photoresist regions 50 are developed bydispensing developer 57 from a dispenser 62 to form a pattern ofphotoresist openings 55, as shown in FIG. 12. The protective layer 20and the exposed photoresist regions are removed by the developer 57 inthis embodiment.

Then as shown in FIG. 13, the pattern 55 in the photoresist layer 15 istransferred to the layer to be patterned 60 using an etching operationand the photoresist layer is removed, as explained with reference toFIG. 7 to form pattern 55″ in the layer to be patterned 60.

In some embodiments, the selective exposure of the photoresist layer 15to form exposed regions 50 and unexposed regions 52 is performed usingextreme ultraviolet lithography. In an extreme ultraviolet lithographyoperation a reflective photomask 65 is used to form the patternedexposure light, as shown in FIG. 14. The reflective photomask 65includes a low thermal expansion glass substrate 70, on which areflective multilayer 75 of Si and Mo is formed. A capping layer 80 andabsorber layer 85 are formed on the reflective multilayer 75. A rearconductive layer 90 is formed on the back side of the low thermalexpansion substrate 70. In extreme ultraviolet lithography, extremeultraviolet radiation 95 is directed towards the reflective photomask 65at an incident angle of about 6°. A portion 97 of the extremeultraviolet radiation is reflected by the Si/Mo multilayer 75 towardsthe photoresist coated substrate 10, while the portion of the extremeultraviolet radiation incident upon the absorber 85 is absorbed by thephotomask. In some embodiments, additional optics, including mirrors arebetween the reflective photomask 65 and the photoresist coatedsubstrate.

The novel protective layer and photolithorgaphy techniques according tothe present disclosure provide improved critical dimension variation andreduces defects. The protective layer prevents the absorption of waterand ammonia and particle contamination of the photoresist duringsemiconductor device processing. Semiconductor devices formed accordingto the present disclosure have improved critical dimension stabilitycontrol. Use of the disclosed protective layer allows the criticaldimension variation to be controlled within a 20% variation. Further,use of the disclosed protective layer provides up to a 10% reduction indefects than conventional techniques. In addition, use of the disclosedprotective layer reduces environmental contamination and provides up toa 5% reduction in exposure dose required to sufficiently expose thephotoresist.

An embodiment of the disclosure includes a method of forming aphotoresist pattern. The method includes forming a protective layer overa photoresist layer formed on a substrate. The photoresist layer isselectively exposed to actinic radiation. The photoresist layer isdeveloped to form a pattern in the photoresist layer, and the protectivelayer is removed. The protective layer includes a polymer havingfluorocarbon pendant groups. In an embodiment, material forming theprotective layer is mixed with photoresist material to form a mixture,and the mixture is disposed over the substrate. In an embodiment, thesubstrate with the mixture disposed thereon is rotated, and theprotective layer separates from the mixture during the rotating andforms the protective layer over the photoresist layer. In an embodiment,the photoresist layer is formed on the substrate and the photoresistlayer is heated prior to forming the protective layer. In an embodiment,the photoresist layer includes metal oxide nanoparticles. In anembodiment, the actinic radiation is extreme ultraviolet radiation. Inan embodiment, photoresist layer and protective layer are heated afterselectively exposing the photoresist layer. In an embodiment, theprotective layer has a thickness ranging from about 0.1 nm to about 20nm. In an embodiment, the contact angle of the protective layer to wateris greater than about 750.

Another embodiment of the disclosure is a method of fabricating asemiconductor device. The method includes supplying a photoresistcomposition to a substrate surface to form a photoresist layer over thesubstrate. A protective layer is formed over the photoresist layer. Thephotoresist layer is patternwise exposed to extreme ultravioletradiation to form a latent pattern in the photoresist layer. Thephotoresist layer is heated after the patternwise exposing. Thephotoresist layer is developed and the protective layer is removedsubstantially simultaneously. The photoresist layer includes a metaloxide, and the protective layer includes a polymer having fluorocarbonpendant groups. In an embodiment, the supplying a photoresistcomposition to the substrate surface, includes mixing the polymer havingfluorocarbon pendant groups with the photoresist composition to form amixture, and supplying the mixture to the substrate surface. In anembodiment, the protective layer is formed by spinning the substratewith the mixture disposed thereon, thereby causing the polymer havingfluorocarbon pendant groups to separate from the mixture and form theprotective layer over the photoresist layer.

Another embodiment of the disclosure is a photoresist compositionincluding a photoresist material, and a polymer having fluorocarbonpendant groups. In an embodiment, the photoresist material includesmetal oxide nanoparticles. In an embodiment, a main chain of the polymerhaving fluorocarbon pendant groups is a polyhydroxystyrene, apolyacrylate, or a polymer formed from a 1 to 10 carbon monomer. In anembodiment, the polymer having fluorocarbon pendant groups comprisesfrom about 0.1 wt. % to about 10 wt. % of one or more polar functionalgroups selected from the group consisting —OH, —NH₃, —NH₂, and —SO₃based on the total weight of the polymer having fluorocarbon groups. Inan embodiment, the polymer having fluorocarbon pendant groups includesfrom about 0.1 wt. % to about 10 wt. % of the fluorocarbon pendantgroups based on the total weight of the polymer having fluorocarbongroups. In an embodiment, the fluorocarbon pendant groups are attachedto a polymer main chain via a linking unit of at least one selected fromthe group consisting of 1-9 carbon unbranched, branched, cyclic,noncylic, saturated, or unsaturated hydrocarbon with optional halogensubstituents; —S—; —P—; —P(O₂); —C(═O)S—; —C(═O)O—; —O—; —N—; —C(═O)N—;—SO₂O—; —SO₂S—; —SO—; —SO₂—; and —C(═O)—. In an embodiment, thefluorocarbon pendant group is selected from the group consisting ofC_(x)F_(y), where 1≤x≤9 and 3≤y≤12; and —(C(CF₃)₂OH). In an embodiment,the polymer having fluorocarbon pendant groups has a weight averagemolecular weight of about 3000 to about 15,000.

The foregoing outlines features of several embodiments or examples sothat those skilled in the art may better understand the aspects of thepresent disclosure. Those skilled in the art should appreciate that theymay readily use the present disclosure as a basis for designing ormodifying other processes and structures for carrying out the samepurposes and/or achieving the same advantages of the embodiments orexamples introduced herein. Those skilled in the art should also realizethat such equivalent constructions do not depart from the spirit andscope of the present disclosure, and that they may make various changes,substitutions, and alterations herein without departing from the spiritand scope of the present disclosure.

What is claimed is:
 1. A method of forming a photoresist pattern,comprising: forming a protective layer over a photoresist layer formedon a substrate; selectively exposing the photoresist layer to actinicradiation; developing the photoresist layer to form a pattern in thephotoresist layer; and removing the protective layer, wherein theprotective layer comprises a polymer having fluorocarbon pendant groups.2. The method according to claim 1, wherein material forming theprotective layer is mixed with photoresist material to form a mixture,and the mixture is disposed over the substrate.
 3. The method accordingto claim 2, further comprising rotating the substrate with the mixturedisposed thereon, wherein the protective layer separates from themixture during the rotating and forms the protective layer over thephotoresist layer.
 4. The method according to claim 1, wherein thephotoresist layer is formed over the substrate and the photoresist layeris heated prior to forming the protective layer.
 5. The method accordingto claim 1, wherein the photoresist layer includes metal oxidenanoparticles.
 6. The method according to claim 1, wherein the actinicradiation is extreme ultraviolet radiation.
 7. The method according toclaim 1, further comprising heating the photoresist layer and protectivelayer after selectively exposing the photoresist layer.
 8. The methodaccording to claim 1, wherein the protective layer has a thicknessranging from 0.1 nm to 20 nm.
 9. The method according to claim 1,wherein the contact angle of the protective layer to water is greaterthan 75°.
 10. A method of fabricating a semiconductor device,comprising: supplying a photoresist composition to a substrate surfaceto form a photoresist layer over the substrate; forming a protectivelayer over the photoresist layer; patternwise exposing the photoresistlayer to extreme ultraviolet radiation to form a latent pattern in thephotoresist layer; heating the photoresist layer after the patternwiseexposing; developing the photoresist layer and removing the protectivelayer substantially simultaneously, wherein the photoresist layercomprises a metal oxide, and wherein the protective layer comprises apolymer having fluorocarbon pendant groups.
 11. The method according toclaim 10, wherein the supplying a photoresist composition to thesubstrate surface, further comprises: mixing the polymer havingfluorocarbon pendant groups with the photoresist composition to form amixture; and supplying the mixture to the substrate surface.
 12. Themethod according to claim 11, wherein the protective layer is formed byspinning the substrate with the mixture disposed thereon, therebycausing the polymer having fluorocarbon pendant groups to separate fromthe mixture and form the protective layer over the photoresist layer.13. A photoresist composition, comprising: a photoresist material; and apolymer having fluorocarbon pendant groups.
 14. The photoresistcomposition of claim 13, wherein the photoresist material comprisesmetal oxide nanoparticles.
 15. The photoresist composition of claim 13,wherein a main chain of the polymer having fluorocarbon pendant groupsis a polyhydroxystyrene, a polyacrylate, or a polymer formed from a 1 to10 carbon monomer.
 16. The photoresist composition of claim 13, whereinthe polymer having fluorocarbon pendant groups comprises from 0.1 wt. %to 10 wt. % of one or more polar functional groups selected from thegroup consisting —OH, —NH₃, —NH₂, and —SO₃ based on the total weight ofthe polymer having fluorocarbon groups.
 17. The photoresist compositionof claim 13, wherein the polymer having fluorocarbon pendant groupscomprises from 0.1 wt. % to 10 wt. % of the fluorocarbon pendant groupsbased on the total weight of the polymer having fluorocarbon groups. 18.The photoresist composition of claim 13, wherein the fluorocarbonpendant groups are attached to a polymer main chain via a linking unitof at least one selected from the group consisting of 1-9 carbonunbranched, branched, cyclic, noncylic, saturated, or unsaturatedhydrocarbon with optional halogen substituents; —S—; —P—; —P(O₂);—C(═O)S—; —C(═O)O—; —O—; —N—; —C(═O)N—; —SO₂O—; —SO₂S—; —SO—; —SO₂—; and—C(═O)—.
 19. The photoresist composition of claim 13, wherein thefluorocarbon pendant group is selected from the group consisting ofC_(x)F_(y), where 1≤x≤9 and 3≤y≤12; and —(C(CF₃)₂OH)—.
 20. Thephotoresist composition of claim 13, wherein the polymer havingfluorocarbon pendant groups has a weight average molecular weight of3000 to 15,000.